From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E97FFC433DF for ; Thu, 4 Jun 2020 23:51:20 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id ACFCE2067B for ; Thu, 4 Jun 2020 23:51:20 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="eREiNyPx" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org ACFCE2067B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 549DC280063; Thu, 4 Jun 2020 19:51:20 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 4ACCC280005; Thu, 4 Jun 2020 19:51:20 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 39B06280063; Thu, 4 Jun 2020 19:51:20 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0175.hostedemail.com [216.40.44.175]) by kanga.kvack.org (Postfix) with ESMTP id 1683B280005 for ; Thu, 4 Jun 2020 19:51:20 -0400 (EDT) Received: from smtpin04.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id C8CE0181AC9BF for ; Thu, 4 Jun 2020 23:51:19 +0000 (UTC) X-FDA: 76893178278.04.rub82_2302ccb26d9b Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin04.hostedemail.com (Postfix) with ESMTP id B1A2B800EEA5 for ; Thu, 4 Jun 2020 23:51:19 +0000 (UTC) X-HE-Tag: rub82_2302ccb26d9b X-Filterd-Recvd-Size: 3472 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf38.hostedemail.com (Postfix) with ESMTP for ; Thu, 4 Jun 2020 23:51:19 +0000 (UTC) Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 6613D208C9; Thu, 4 Jun 2020 23:51:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591314678; bh=B4kb3T1Snxx3JqVxX5bTsGbZxR/h7AxRoi0JZrXvIwQ=; h=Date:From:To:Subject:In-Reply-To:From; b=eREiNyPxPnwu1fSCFY74naMvdbFPcGu1lRx1YvT0Bre1Y/pDPukTAMzDWD7Ac6M/J F7j0dME4IB6Tl9NBOnYgK/tM9/aCCRLT/AJZOwKV4Rb0GIYEh1qxEGi2Y1B+OWy16r 6rSmi9h3JzBf5QbksimZ4M+zN+C1seoIl8oUfOnw= Date: Thu, 04 Jun 2020 16:51:18 -0700 From: Andrew Morton To: akpm@linux-foundation.org, hch@lst.de, linux-mm@kvack.org, mm-commits@vger.kernel.org, torvalds@linux-foundation.org, viro@zeniv.linux.org.uk Subject: [patch 097/127] exec: open code copy_string_kernel Message-ID: <20200604235118.7QWRd3RgW%akpm@linux-foundation.org> In-Reply-To: <20200604164523.e15f3177f4b69dcb4f2534a1@linux-foundation.org> User-Agent: s-nail v14.8.16 X-Rspamd-Queue-Id: B1A2B800EEA5 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam04 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: Christoph Hellwig Subject: exec: open code copy_string_kernel Currently copy_string_kernel is just a wrapper around copy_strings that simplifies the calling conventions and uses set_fs to allow passing a kernel pointer. But due to the fact the we only need to handle a single kernel argument pointer, the logic can be sigificantly simplified while getting rid of the set_fs. Link: http://lkml.kernel.org/r/20200501104105.2621149-3-hch@lst.de Signed-off-by: Christoph Hellwig Cc: Alexander Viro Signed-off-by: Andrew Morton --- fs/exec.c | 45 +++++++++++++++++++++++++++++++++++---------- 1 file changed, 35 insertions(+), 10 deletions(-) --- a/fs/exec.c~exec-open-code-copy_string_kernel +++ a/fs/exec.c @@ -592,17 +592,42 @@ out: */ int copy_string_kernel(const char *arg, struct linux_binprm *bprm) { - int r; - mm_segment_t oldfs = get_fs(); - struct user_arg_ptr argv = { - .ptr.native = (const char __user *const __user *)&arg, - }; - - set_fs(KERNEL_DS); - r = copy_strings(1, argv, bprm); - set_fs(oldfs); + int len = strnlen(arg, MAX_ARG_STRLEN) + 1 /* terminating NUL */; + unsigned long pos = bprm->p; - return r; + if (len == 0) + return -EFAULT; + if (!valid_arg_len(bprm, len)) + return -E2BIG; + + /* We're going to work our way backwards. */ + arg += len; + bprm->p -= len; + if (IS_ENABLED(CONFIG_MMU) && bprm->p < bprm->argmin) + return -E2BIG; + + while (len > 0) { + unsigned int bytes_to_copy = min_t(unsigned int, len, + min_not_zero(offset_in_page(pos), PAGE_SIZE)); + struct page *page; + char *kaddr; + + pos -= bytes_to_copy; + arg -= bytes_to_copy; + len -= bytes_to_copy; + + page = get_arg_page(bprm, pos, 1); + if (!page) + return -E2BIG; + kaddr = kmap_atomic(page); + flush_arg_page(bprm, pos & PAGE_MASK, page); + memcpy(kaddr + offset_in_page(pos), arg, bytes_to_copy); + flush_kernel_dcache_page(page); + kunmap_atomic(kaddr); + put_arg_page(page); + } + + return 0; } EXPORT_SYMBOL(copy_string_kernel); _